Electro-fluid systems



pia! 15, 1 H.HuRv\-fz 3,438,384

ELECTED-FLUID SYSTEMS 7 Filed July 15, 1960 SUMF' ATTORNEYS United States Patent 3,438,384 ELECTRO-FLUID SYSTEMS Hyman Hurvitz, 1313 Juniper St. NW., Washington, DC. 20012 Filed July 15, 1960, Ser. No. 43,162 Int. Cl. F1-5c N US. Cl. 137-81.5 28 Claims The present invention relates generally to fluid amplifiers, flip-flop, oscillators and the like, and more particularly to fluid amplifiers having electrical inputs and outputs.

Pneumatic and hydraulic systems as generally employed in the prior art have utilized moving elements such as pistons, valves, diaphragms or vanes to accomplish their purposes. In all such cases the use of moving parts introduces system limitations because of friction, wear, thermal expansion, inertia and weight of parts, and furthermore introduces a considerable item of cost in manufacture, and renders the design of extremely small fluid systems diflicult because of the fragility of the parts when they are small. Elimination of moving parts introduces reliability, ruggedness, long storage life, high speed of operation, and freedom from maintenance, and facilitates the design of extremely small fluid control units.

It has been discovered that a fluid system having no moving parts other than the fluid can be constructed and can have amplifying properties, in the sense that the proportion of the total energy of a fluid stream delivered to a given output orifice or utilization device can be controlled in response to a further fluid stream possessing lesser total energy of flow. Systems of this type are generally denominated pure fluid amplifiers. In the prior art such pure fluid amplifiers have not involved electrical input signals or electrical output signals, i.e., such devices have required mechanical or electromechanical transducers for effecting changes in fluid flow, and pistons or vanes or diaphragms for responding to changes in fluid flow. Where electrically operated devices have been utilized as input transducers or output transducers, they have been electromechanical devices involving use of moving parts.

It is a primary object of the present invention to provide a fluid amplifier having no moving parts, and wherein electrical input energy can be utilized to control fluid input signals to the device without interposition of moving parts and wherein electrical circuits can be utilized as transducers to detect fluid flow in the amplifiers having no moving parts.

It is another object of the present invention to provide a closed loop fluid amplifier system, wherein the fluid is an ionizable gas operated at very low pressure, so that it may be readily ionized and emit light.

Fluid devices heretofore designed and operated have operated with liquid as the fluid or with gas as the fluid. When they have operated with gas as fluid, the gas has been at a pressure, somewhere in the system, equal to or above atmospheric. In no case has the pressure been so low that the gas involved may be readily ionized. In accordance with the present invention the gas employed may be helium, neon, argon, or combinations of these, or the like, operated at a sufliciently low pressure that the gas may be ionized and become conductive in response to relatively small voltages, or emit light in response to electromagnetic radiation fields. If the entire body of gas in the device is ionized and emits light, as by operating a relatively high frequency oscillator adjacent to the device, then the flow patterns of the gas in the device may be readily observed, since the degree of ionization of a gas and hence the amount of light emitted depends upon its pressure, everything else being equal. Where the gas in the device is at relatively low pressure it will be more intensely ionized, and where the gas is at higher pressure'it will be less intensely ionized. This provides a valuable research tool in permitting visual observation of pressures and flow patterns at all points of the system.

It is accordingly an object of the present invention to provide a system for facilitating the visual observation and study of fluid amplifiers operating at low fluid pressures and of fluid pressures at various points thereof, where the fluid is an ionized or ionizable gas.

Additionally, amplifiers in accordance with the invention may be operated as multivibrators or flip-flops, i.e., as bi-stable' devices which may be triggered from an ex ternal signal. Such devices may also be self-oscillatory. Such bi-stable devices may be utilized as basic components of computers, and in such case it becomes important to know what the state of the oscillator or bi-stable device may be, i.e., to provide a visual read-out. The state of a bi-stable fluid device is determined by the relative pressures in two passages, i.e., fluid is directed into one or the other of the passages under relatively high pressure, the other passage remaining at relatively low pressure. The present invention provides a simple device for visually indicating the state of a 'hi-stable device, since if the passages have transparent walls that passage in which fluid flow is at low pressure will be more highly ionized than the passage in which fluid flow is at high pressure, and hence will glow, and in fact, gas in the latter passage may be deionized entirely and not glow. The low pressure passage will glow and the other will not, to provide a readout.

It is a further feature of the present invention to provide input or control signals for a fluid amplifier or bistable element, without requiring utilization of electromechanical transducers.

In accordance with the invention, variable fluid resistors, which are voltage responsive, are utilized in the control jet passages or in the feed-back passages of histable or oscillatory fluid amplifiers. Such fluid resistors are constituted of elongated spaced electrodes, having relatively small spacing, between which the fluid must flow longitudinally. Particularly when the fluid is ionized gas, the resistance to passage of the fluid through the narrow passageways can be made extremely high in response to application of suflicient voltage to the electrodes. Resistance is a direct function of the voltage applied, for a given electrode spacing, and a direct function of the lengths of the spaced elongated electrodes.

In accordance with a further feature of the invention spaced point electrodes are placed in the output passages of the amplifier, although electrodes which are elongated in the direction of the length of the passages may be employed if desired, and if employed provide greater current flow in associated circuits. Across each pair of electrodes is provided a source of voltage and a load device. The load devices may 'be relays, resistances, input circuits of transistors or vacuum tubes, or the like. It then becomes possible to operate relays, for example, in response to fluid bi-stable devices or amplifiers or oscillators, and to control the latter in response to the application of electrical control signal, there being no moving parts in the entire system except such moving contacts as may be associated with the relays when utilized. Moreover, the current flowing in the load may be a replica of the control signal.

The utilization of extremely low pressure ionizable gas as the fluid in a fluid system involves a fluid system which is completely closed, i.e., the amplifier output passages feed into a sump, which feeds into a pump, which in turn supplies gas under pressure to a power jet of the amplifier. This arrangement permits extremely stable ambient pressures, and also high speed of operation of the amplifier or =bi-stable device, since the inertia of the fluid is a limiting factor in obtaining speed of operation, and by utilizing extremely low pressure fluid this factor may be essentially eliminated. Speeds may then be obtained in the vicinity of 50,000 c.p.-s. or more. Such systems are more economical to build than corresponding systems employing transistors or vacuum tubes, in addition to their other advantages, i.e., reliability, ruggedness, capability of operating under extreme temperature conditions and low cost and small size. There is a further advantage when such systems are operated as parts of computers, which is that they provide their own visual status indication, so that read-out devices are not required apart from the bi-stable devices of the computer, for visual read-out. The output and input of the fluid amplifier or bi-stable device may be electrical, just as in the case of vacuum tube or transistor or other types of amplifiers or bi-stable circuit elements, which leads to great system flexibility.

Provision of electrical input and output systems having no moving parts, for use in fluid amplifiers having no moving parts, renders possible the hybridization of fluid electrical systems to an extent heretofore never known, and at speeds of operation beyond those currently available by a factor of several orders of magnitude. An appropriate descriptive term for such devices is electrofluid.

Fluid amplifiers utilized in the practice of the present invention may be of various types. One such type is known as the stream interaction or momentum interchange type. In such a system a power nozzle is supplied with pressurized fluid and issues a power jet or stream. A control jet directs fluid against the side of the power jet and deflects the power jet away from the control jet. Momentum is conserved in the system, and the power jet will therefore flow at an angle with respect to its original direction such that the tangent of this angle is a function of the momentum of the control stream and the momentum of the power stream. It is thus possible to direct a high power jet toward or away from a target area in response to a control stream of lower power.

A further type of fluid amplifier is known as the boundary layer fluid amplifier. Boundary layer fluid amplifiers direct high energy power jets directly toward a target area or receiving aperture system, by the pressure distribution in the power jet boundary layer region. This pressure distribution is controlled by the wall configuration of an interaction chamber, i.e., a chamber in which the power jet and control jets interact, as well as by power jet energy level, fluid transport efiects, backloading of the amplifier outputs, and the flow of control fluid to the boundary layer region. Whereas side walls are not essential for operation of interaction type fluid amplifiers, a boundary layer control fluid amplifier requires the use of side walls for control of the power jet. In a boundary layer control fluid amplifier special design of the interaction chamber configuration assure that the power jet will lock onto one side wall, and remain in lock-on configuration even without control fluid flow. When the power jet is suitably deflected toward one side wall by a control fluid jet it can lock onto that side wall and remain in the locked-on configuration even after the control fluid is stopped. The unit thus possesses positive feedback inherently by virtue of the lock-on configuration of the interaction chamber, and the feed-back path is created and destroyed in accordance with the position of the power jet. In essence, this implies that power jets may be deflected to one side or the other of the interaction chamber in response to a pulse of control jet pressure, and having been so deflected will remain in its deflected position until that position is disturbed by the application of sufficient pressure to an appropriate control jet. Such amplifiers lend themselves admirably to provision of bi-stable devices, or flip-flops, since they are inherently stable in either of two configurations. They also lend themselves to the production of multivibrators.

It is an object of the present invention to provide a fluid amplifier, of the boundary lock-on type, in which control may be effected electrically by means of a transducer having no moving parts, in which output signal may be derived from the amplifier by means of a transducer having no moving parts, and in which, furthermore, extremely low pressure gas of an ionizable type may be employed as a fluid, whereby fluid flow paths and pressures in the device passages may be readily visually observed and studied in an effort to improve design of the device, and may also 'be utilized to increase the speed of operation of the device, and to provide inherent visual read-outs, by virtue of the light emitting properties of ionized gas.

The fact that a device according to the present invention can be electrically controlled, renders possible modulation of frequency when the device is adjusted to be self oscillatory, and also renders possible pulse length modulation of its output, all in response to electrical signals. Provision of frequency modulated oscillators and of pulse length modulated fluid pulses is a feature of the invention.

The above and still further objects, features and advantages of the present invention will become apparent upon consideration of the following detailed description of one specific embodiment thereof, especially when taken in conjunction with the accompanying drawings, wherein:

The single figure of the drawing is a schematic representation of a fluid amplifier according to the invention, arranged to operate as a bistable device or as a controlled oscillator, and to provide visual read-out, and electrical inputs and outputs.

Referring now more specifically to the drawings there is illustrated a channel 10, which leads into a power chamber 11 having at its output a power nozzle 12. Fluid is supplied to the channel 10 from a pump 12, which is supplied with fluid in turn via a tube 13 from a sump 14. The fluid amplifier, generally denominated by the reference numeral 15, derives fluid under relatively higher pressure from the pump 12'. The fluid flows through the amplifier 15 and into the sump 14, and is returned from the sump 14 to the pump 12 for return to the power chamber 11. The system, accordingly, is a closed system, i.e., a fixed amount of fluid is supplied thereto initially at fixed pressure, and this fluid remains operative within the system at all times. The fluid utilized in the present embodiment of my invention is a very low pressure gas, the pressure being measurable in millimeters of mercury, so that the gas may be readily ionized and will glow either by application of suitable voltage across any portion of the flow path, or the entire unit may have its gaseous content ionized to provide visible light by operation of an electromagnetic oscillator 16 in its vicinity. The fluid stream issuing from the power nozzle 12 is divided into two streams (when the stream is undeflected), by a divider 20, which may be symmetrically located with respect to the nozzle 12. On either side of the divider 20 are provided passages 21 and 22, which may proceed to the sump 14. If the fluid stream is deflected to the right (as seen in the drawings), fluid flows to the passage 22 and no longer flows to the passage 21, whereupon the fluid is at relatively high pressure in the passage 22 and relatively low pressure in the passage 21. On the other hand if the fluid stream is deflected to the left, the fluid flows through the passage 21 and does not flow through the passage 20, whereupon pressure in the passage 22 becomes low and pressure in the passage 21 relatively high. Communicating with the passages 21 and 22 are feed-back paths 23 and 24, respectively, in the form of very small bore channels or pipes. The channel 23 proceeds to a relatively large chamber 25 which constitutes a fluid capacitance, the channel 23 itself constituting a fluid inertance. Similarly, the channel 24, which constitutes a fluid inert and is of the same size and shape as the channel 23, communicates with a relatively large chamher 26 which has the same capacitance as the chamber 25. The chambers 25 and 26 communicate with elongated power nozzles 27 and 28, which communicate in turn with an interaction chamber 29 into which the power jet issues from the power nozzle 12. The points of egress of the control nozzles 27 and 28 are set back from the edge of the power nozzle 12, to provide a boundary layer effect. This effect occurs because in travelling from the power jet 12 the stream of fluid entrains particles of fluid located adjacent to the egress points of the power nozzles, and thereby reduces the pressure adjacent to the power nozzles, and also because of the shapes of the walls 30, 31, of the interaction chamber 29. In net result the stream of fluid issuing from the power jet 12 tends to lock on to one or the other of the walls 30, 31. This lock-on feature is not this applicants invention but is, per se, known in the art.

The system as described to this point is a bistable device, in the sense that the power jet remains in either of its deflected positions when translated into such position, provided the feed-back paths 23, 24, are inoperative. The feed-back paths 23, 24, when open, can constitute the device an oscillator or multivibrator, the frequency of oscillation of which is determined by the inert of the channel 24 and the capacity of the capacitance 26, as well as the inertia of the channel 23 and the capacity of the capacitance 25.

In operation, if we assume that the jet issuing from the power nozzle 12 has locked on the right wall, relatively high pressures will exist at the input to the channel 24, and relatively low pressure at the nozzle 28, i.e., at the egress of the channel 24. The difference in pressure results in flow around the channel, which consumes some definite time, depending on the length of the channel and the cross sectional area of the channel, this flow eventually building up pressure in the capacitance 26. When the pressure in the latter is sufficient, the pressure present in the egress of the nozzle 28 is overcome by flow from the capacitance 26, and the power stream then deflects to the wall 30. The process is repeated, by the channel 23 and the capacitance 25, so that in due course the stream is' again deflected to the right wall 31. This process continues indefinitely, and if the inertia and the capacitances and the two feed-back paths are equal, the oscillations generated will have equal half-cycles.

The system as described to this point, by reference to the accompanying drawings, is known and is not the invention of applicant, in respect to its structural features, except in respect to the utilization of a completely closed system and in respect to the ultilization of ionizable gas at extremely low pressure as the fluid.

If, now, the system is operating as such, or if the oscillator is in one of its bi-stable states, which may be accomplished by blocking one of the feed-back paths 23, 24, or one of the nozzles 27, 28, and if the oscillator 16 is operating in sufficient intensity, the gas in all the passages of the amplifier may become ionized. The degree of ioniza tion will depend upon the pressure of the gas at each point in the amplifier. Low pressure gas tends to ionize more readily and g-low more brightly than does higher pressure gas, and accordingly if the amplifier is made so that its passageways are readily visible, excellent qualitative deductions may be provided as to the character of the operation of the system by visual observation thereof. Such information is invaluable in enabling design of improved systems by improving the contours of aerodynamic surfaces, and by indicating the changes in operations of the systems when they are designed for different frequencies and/ or different pressures of the fluid.

The use of ionized gas in this respect has a further advantage when the system is operative as a bi-stable device, say as part of a computer. In such case visual ob servation of the gas channel 21, 22, automatically provides visual indication of the state of the device, i.e., whether the gas is passing through channel 21 or through channel 22, at high pressure. The illumination provided may be utilized to illuminate numerals of a numeral indicator, should the present system become part of a complex computer, or the passages 21, 22, may, if desired, be shaped in the form of transparent numerals, letters or the like.

In the passage 21 is located a pair of separated electrodes 40, 41, which communicate with a source of voltage 42 and a load 43, in a series circuit. Load 43 may constitute a relay, or the input circuit of a transistor or vacuum tube, or a transducer of any desired type. Similarly a pair of spaced electrodes 44, 45, exists in the passage 22, which are connected to a source of voltage 46 and a load device 47 in series. Load 47 may be the same as or different than load 43. By proper choice of strength of the electromagnetic field provided by the oscillator 16 it is possible to maintain ionization only in that passage.

having the smaller pressure. In either event transfer of fluid flow from one to ther other of the passages 21, 22 results in change in current in the loads 43, 47. It is also possible to cut off the oscillator 16 completely, and to provide such voltage at 42 and at 46 that the voltage itself ionizes the gas in the passages 21, 22, when the latter are snfliciently reduced in pressure, but does not ionize the gas when the pressure is relatively high.

This constitutes, apart from the field of fluid amplifiers, a novel form of switch. So far as I am aware, no prior art exists showing a switch within or without a fluid amplifier, which operates in response to changes of pressure of a gas, without the interposition of mechanically moving parts.

Coating the channel 23 are two relatively insulated but elongated electrodes 50, 51. The electrode 50 is connected to ground while the electrode 51 is connected to a variable voltage source generally indicated at 52 by a battery and potentiometer. Similarly the channel 24 includes a'pair of elongated relatively insulated electrodes 55 and 56 of which the electrode 55 may be grounded and the electrode 56 connected to a source of variable voltage 57, constituted of a battery and'a parallel potentiometer. It will be realized that the voltage sources 52, 57 may be of any desired character such as audio amplifiers, transducers, or the like, and that the specific simple variable voltage sources shown in the drawings are to simplify the exposition. It is now the case that gas passing through the feedback channel 23, and similarly for the channel 24, must pass between the electrodes 50, 51. These electrodes constitute a variable fluid resistance, because ionized gas passing between the electrodes tends to slow down because the molecules of the gas are attracted to the electrodes. The specific resistance introduced is a function of the spacing of the electrodes, the length of the electrodes and the voltage applied. Accordingly the resistance of either one of the channels 23, 24 may be electrically modified. Such modification results in a change in frequency of the system, if the system is operating as an oscillator and also may be utilized to introduce relative pulse length modulation of the output of the oscillator by introducing different resistances in the two channels 23, 24, so that the times the power jet occupies in channels 21, 22 may be relatively different.

If the pressure oscillations in channels 21, 22 are considered a carrier, audio rate modulation of the voltage sources 52, 57, as in response to a microphone or audio amplifier, can be used to frequency modulate the carrier, if both fluid resistances are correspondingly modified, and to provide for pulse duration modulation or pulse position modulation, if they are varied differentially.

The channels lea-ding to the control jets 27, 28 may similarly be provided with relatively insulated electrodes,

justable fluid resistances in series with the control nozzles,

and by adjusting these resistances the total pressures which must be built up in the capacitances 25, 26, in order to cause transfer of stable state of the system, may be adjusted or varied. Accordingly, the variable voltage sources 65, 66 may be utilized to frequency modulate the output of the system, or to change the relative durations of the half periods of the system. Similarly the resistances may be sufliciently greatly increased to cut off the high stable device in either of its bi-stable states, since the power jet cannot be deflected away from that control nozzle which is incapable of providing sufficient power to overcome the negative pressure produced by the hydrodynamic configuration of the walls 30, 31 and the locations of the nozzles 27, 28 with respect to the power nozzle 12.

It is within the confines of the inventive concept of my invention, to connect systems such as 15 in cascade electrically, by utilizing the electrical output of one amplifier or bi-stable device to control the operation of the next amplifier or bi-stable device in the cascaded series, and also to enable systems such as that illustrated at 15 to be operated remotely by electrical control systems. It is considered obvious that voltage developed across loads 43, 47 may be utilized to control the voltage in fluid electrical fluid resistances, such as those provided by the electrodes 50, 51 or 60, 61, in a chain of bi-stable devices. The voltages across the loads 43, 47 may also be utilized to excite a resonant circuit, which may be extremely high Q, and the output of the latter may then be utilized to control the frequency of the oscillator 15, whereby the oscillator, instead of relying upon the physical constants of the inertia 24 and the capacitance 26, as well as the various fluid resistances in the system, for controlling its frequency, may have its frequency controlled electrically by means of a tuned circuit, such as a piezoelectric crystal.

By proper selection of spacing of electrodes (as 40, 41 or 44, 45) and of voltages of sources 42, 46, and of gas pressures, it is feasible to arrange that current flow in loads 43, 47 may be replicas of input signals, depending then on gas pressures. If gas pressure in channel 22, for example, varies sinusoidally, without ever saturating or cutting off current flow between electrodes 44, 45, that current flow will be sinusoidal.

While I have described and illustrated one specific embodiment of my invention, it will be clear that variations of the details of construction which are specifically illustrated and described may be resorted to without departing from the true spirit and scope of the invention as defined in the appended claims.

I claim:

1. A fluid amplifying device, comprising a fluid pump, a power nozzle coupled to said pump, said power nozzle being arranged to direct a first stream of said fluid generally in a first direction, at least one fluid control nozzle arranged to communicate with and directed transversely of said first stream of said fluid downstream of said nozzle, said fluid being an ionizable gas, and means for ionizing said gas in at least a portion of its flow path.

2. The combination according to claim 1 wherein is provided at least one return fluid path for returning said fluid in said stream to said pump.

3. The combination according to claim 2 wherein said pump, said nozzles, said pump and said return path constitute a completely closed system, wherein said fluid is continuously recirculated.

4. The combination according to claim 3 wherein said gas in said completely closed system has an ambient pressure of less than one centimeter of mercury.

5. In combination, a fluid path including a nozzle having in said path a pair of electrodes having a predetermined spacing, means directing gas in said path, a source of voltage connected across said spaced electrodes, a load in circuit with said source of voltage and said electrodes, and means for selectively raising and lowering the pressure of said gas below and above ionizing pressure for the specific electrode spacing and voltage, whereby selectively to make and break the circuit to said load.

6. A fluid amplifying system, comprising a closed gas circulating system comprising a pump, a fluid amplifier amplifying flow of said gas and a sump, all connected in a closed loop, said gas in said sump having an ambient pressure less than atmospheric pressure.

7. The combination according to claim 6 wherein said fluid amplifier includes a pair of alternate paths for said gas, means for directing said gas under pressure to said paths selectively in alternation, whereby one of said paths may contain higher pressure gas while the other of said paths contains lower pressure gas, and a pair of separated electrodes in each of said paths.

8. The combination according to claim 7 wherein is provided a source of voltage connected across at least one of said pairs of electrodes, and a load device connected with said electrodes, said gas when ionized providing a current path to said load.

9. A fluid operated system, comprising a fluid flow amplifier including a nozzle and a fluid flow deflector device and a fluid flow receptor, said fluid being a gas at ambient pressure less than 1 cm. of mercury.

10. A fluid flow multivibrator, comprising a fluid flow bistable device having a nozzle and arranged to oscillate said flow at a predetermined frequency, and means to vary said frequency comprising a path for said fluid flow having a voltage gradient thereacross.

11. A fluid flow operated system having fluid flow passages wherein the fluid is ionizable gas, translucent walls in at least some of said passages, means operatively associated with at least some of said passages for ionizing the gas in said some of said passages only when said gas in said some of said passages is below a predetermined pressure, and means for modifying the pressures of said gas in all said passages selectively above and below said predetermined pressure.

12. A fluid flow amplifier, said amplifier including at least a power nozzle for providing a free jet of fluid di rected in a first direction, and means for developing a fluid pressure differential transversely of said jet, wherein is provided a pair of channels for conducting said jet differentially according to the direction of said pressure differential, wherein said channels include at least a translucent wall, and wherein said fluid is directly observable.

13. The combination according to claim 12 wherein said fluid is a light emitting fluid.

14. An electrical amplifying method, comprising varying gas pressure between predetermined limits in response to an input signal, and detecting current flow in a circuit between spaced electrodes immersed in the gas responsive to the variations in gas pressure.

15. An amplifier, comprising a source of ionized gas including a nozzle, a pair of electrodes immersed in the gas, a source of voltage, a load device, said pair of electrodes, said source of voltage and said load device being interconnected so as to permit current flow in said load as a function of electrical resistance in a path through said gas between said electrodes and means for varying the pressure of said gas in response to an input signal to said amplifier.

16. A fluid amplifying device, comprising a fluid pump, a power nozzle coupled to said pump, said power nozzle being arranged to direct a first stream of said fluid generally in a first direction, at least one fluid control nozzle arranged to communicate with and directed transversely of said first stream of said fluid downstream of said nozzle, said fluid being an ionizable gas, and means for ionizing said gas in at least a portion of its flow path, at least one return fluid path for returning said fluid in said streams to said pump, said pump, said nozzles, said pump and said return path constituting a complete closed system, wherein said fluid is continuously recirculated, said gas in said completely closed system having an ambient pressure of less than one centimeter of mercury, and a source of electromagnetic radiation adjacent to said at least a portion of its flow path.

17. A fluid amplifier, including a source of a stream of said fluid, at least one receptor for said stream of fluid,

said stream of fluid being normally directed toward said receptor, a control nozzle for issuing fluid in deflecting relation to said stream of fluid, a feedback channel connected between said receptor and said control nozzle, a source of control signal, said source of signal being external of said amplifier, and means responsive to said control signal for controlling the flow of fluid in said feedback channel.

18. A pure fluid oscillator system, comprising a source of a stream of fluid, receptor means for said fluid, means for alternately varying the direction of said stream in alternate senses with respect to said receptor at a predetermined rate, and means for varying said rate, a sourceof control signal said source being external of said oscillator, said last means being responsive to said control signal.

19. A pure fluid system, comprising a source of a stream of fluid, receptor means for said stream of fluid, means for varying the direction of said stream of fluid with respect to said receptor means, feedback means coupling said receptor means with said means for varying the direction of said stream of fluid, said feedback means constituting at least one fluid delay line, a source of signal, said source of signal being external of said system, means for impressing a sequence of signals from said source of signals on said at least one delay line, and means for reading out the output of said amplifier.

20. The combination according to claim 19 wherei said means for impressing a sequence of signals comprises means for controlling the fluid impedance of said at least one delay line.

21. The combination according to claim 19 wherein is provided electrically responsive means for controlling the fluid impedance of said at least one delay line.

22. The combination according to claim 19 wherein said means for reading out is an electrical means.

23. In a fluid amplifier of the type having a power nozzle for forming a free power jet, a generally wedge shaped jet divider having its apex facing upstream toward said nozzle, said jet divider providing boundaries for plural output ducts, the improvement comprising:

first means for ionizing the fluid in said power jet, and second electrical means disposed about the path of said free power jet for selectively generating a field for directing said free power jet selectively to said output ducts.

24. In a bistable fluid amplifier of the wall effect type having nozzle means connected to a source of fluid power for producing a power jet, means forming a pair of output passages for receiving said power jet, and means defining an interaction chamber interposed between said nozzle means and said output passages including a pair of boundary walls associated respectively with said output passages, improved control means for said amplifier comprising:

(a) means defining a pair of channels associated respectively with said boundary walls each terminating in a control port of reduced dimensions adjacent said nozzle means,

(b) said ports providing fluid communication between said interaction chamber and said channels, and

(c) means located in each of said channels remote from said interaction;cl1amber and said power jet for producing an electrical discharge operable to selectively switch said power jet from one of said output passages to the other.

25. In the fl'uid amplifier of claim 24; said discharge producing means comprising a pair of electrodes.

26. In a fluid amplifier of the type having a power stream input duct for receiving a fluid stream and a plurality of output signal ducts, the improvement compris- 1ng: I

(l) first electrical means for ionizing the fluid which flows through said power stream input duct;

(2) and second means disposed adjacent the path of said ionized power stream for selectively directing said stream to one of said output signal ducts, wherein is further included means in at least one of said output signal ducts for detecting presence of ionized fluid.

27. In a fluid amplifier of the type having a power stream input duct for receiving a fluid stream and a plurality of output signal ducts, the improvement comprismg:

(1) first electrical means for ionizing the fluid which flows through said power stream input duct;

(2) and second means disposed adjacent the path of said ionized power stream for selectively directing said stream to one of said output signal ducts, wherein is provided means in said output signal ducts for selectively responding electrically to degree of ionization of fluid in said output signal ducts.

28. In a fluid amplifier of the type having a power stream input duct for receiving a fluidstream and a plurality of output signal ducts, the improvement comprislng:

(1) first electrical means for ionizing the fluid which flows through said power stream input duct;

(2) and second means disposed adjacent the path of said ionized power stream for selectively directing said stream to one of said output signal ducts, wherein is provided means for distinctively visualizing the extent of ionization of said fluid in said output signal ducts.

References Cited UNITED STATES PATENTS 2,763,125 9/1956 Kadosch et al 13781.5 X 3,024,805 3/1962 Horton 137-815 3,036,430 5/1962 Eggers et al 239265.23 3,185,166 5/1965 Horton et al. 137--81.5 3,295,543 1/1967 Zalmanzon 137'81.5

FOREIGN PATENTS 64,773 6/ 1955 France.

SAMUEL SCOTT, Primary Examiner. 

1. A FLUID AMPLIFYING DEVICE, COMPSIRING A FLUID PUMP, A POWER NOZZLE COUPLED TO SAID PUMP, SAID POWER NOZZLE BEING ARRANGED TO DIRECT A FIRST STREAM OF SAID FLUID GENERALLY IN A FIRST DIRECTION, AT LEAST ONE FLUID CONTROL NOZZLE ARRANGED TO COMMUNICATE WITH AND DIRECTED TRANSVERSELY 